[Mimedefang] Re: Great open letter about anti-virus, emails, bounces, etc.

[Royce Williams]

Michael Sims wrote:
> ...to go away and use their ISP's mail relay to send their mail.  I'm afraid
> if I do this that I'll run across some fly-by-night company that's too cheap
> to get a decent hosting solution and is trying to run a business off a
> residential dynamic connection.  And it'll be my luck that this will be a
> client that one of my end users will swear they need to do business with.

We maintain an extensive "mini-DUL" with reverses for IPs that are known to be
dynamically allocated in our sendmail access file.

We've had good luck with kicking back a 550 that simply says "Mailing directly
from dynamics refused; please use your provider's outgoing mail server to
relay."  Even if they're a fly-by-night keeping costs down, all they have to
do is use the mail server that their connectivity already (almost always)
includes.  For the few exceptions where Layer 8 has insisted that we allow it,
we simply do so at the sendmail level.  This is pretty rare, though; most legit
folks seem to catch on without too much trouble and make the switch.

Royce